Compressor unloader



Sept. 28 1926.. 1,661,211

HI.,\ V. HAIGHT COMPRESSOR UNLOADER FiledOot. I4 1925 INVENTOR HIS ATTORNE Patented Sept. 28, 1926.

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HARRY V. HAIGHT, F SHERBROOKE, QUEBEC, CANADA, ASSIGNOR T0 INGERSO LL- RAND COMPANY, OF JERSEY CITY, NEW- JERSEY, A CORPORATION OF NEW JERSEY.

COMPRESSOR UNLO'ADERH;

Application filed October 14, 19 25. Serial No. 62,398.

' This invention relates to'com'pressor unloaders of the step-by-step type, and the objects of the invention are to produce a simple and eificient unloaderwhich is cheap, to

manufacture and capable of unloading the compressor step-by-step automatically and again loading it, preferably controlled by the discharge pressure.

The invention is applicable to any com-- pressor cylinder whether single or double acting, duplex or compound, and. may be termed a free air unloader because several of the unloading steps are effected by holding one or more of the inlet valves open. 1n

accordance with" this invention, however, the

,- first step of'unloading is effected by means Referring to the drawin s, the low pressure cylinder A and the hig pressure cylinder B are provided. with the pistons C and D having the piston rods E and F adapted to be driven in any suitable manner from a motor or engine not shown. The discharge G of the low pressure cylinder is connected in the usual manner through the intercooler H to the inlet J of the high pressure cylinder, and the inlet of the low pressure cylinder is indicated at K. The discharge L of the high pressure cylinder is connected to the usual receiver 0 by the pipe P.

The air head at the head end of 'eachcylinder is rovided witha single clearance chamber and R, communication between which chambers and theirrespective cylinders is controlled b the clearance valves S and T, which may e ordinary plate valves adapted to be held open in any suitable manner when required, as by means of the valve openers U andV having fingers W andX adapted to bear against the valves and hold them open. Springs Y and Z normally hold the fingers retracted, and the valve openers are in this instance provided with the pistons a: and b in the cylinders o and d, which are connected by ipes 6 and f to the common pipe 9 which is in turn connected through the auxiliary valve h and pipe 9' to v the receiver 0.

The cylinders A and B are provided with suitable inlet and discharge valves, which may be of the plate type, and as shown, the

inlet valves is and 0 of the low pressure cylinder are provided with the valve openers p and 9 similar to those-described in connection with the clearance valves. The inlet valves 7' and s of the high pressure cylinder are also provided with the valve openers t and u of similar construction. The discharge valves 'v of both cylinders may be of any suitable construction and are shown as plate valves.

The cylinders '20 of the inlet valve openers at the clearance ends of the cylinders are respectively connected by the pipes m' and y to the common pipe .2, which is in turn connected to the auxiliary valve 3 and thence I through the pipe 4 tothe receiver 0. The

cylinders 5 of the valve openers of the inlet valves on'the opposite ends of the cylinders are respectively connected by thepipes 6 and 7 to the common pipe 8, which is connected through the auxiliary valve 9 and pipe 10 to the receiver 0.

The auxiliary valves referred to may be of any suitable construction for causing antomatic and successive operation of the various. valve openers in accordance with the discharge pressure, andjt is to be understood that a valvcof the type shown in' U. S. Pate out No. 1,138,278 granted May 4, 1915, to J.

H. Castle and W. G. Rogers, may be used,

which is so constructed that the valve operates to admit a certain predetermined receiver pressure to the appropriate unloading mechanism pntil the receiver pressure again falls a-certaln amount below that required to operate the valve, in which case the valve returns to its original position, allowing the unloading mechanism to exhaust to atmospheric pressure.

On each of the auxiliary valves h, 3 a d- 9 in the drawing I .have indicated the adjustable valve plugs 14 and the spring cups 28 corresponding to similar parts similarly numbered in said patent, it being understood that any other suitable auxiliary valve op:

crating as a pilot valve may be used inthe locations mdicated by valves h, 3 and 9,

since .the particular construction of valve forms no part of the present invention.

In the operation of the apparatus letit ioo be assumed thatthe compressor is operating at full load with all clearance valves closed and the inlet valves functioning normally,-

load. When the first auxiliary valve h operates to admit pressure to thevalve openers of the clearance valves S and T, at the head end of the cylinders,- said clearance valves will be simultaneously opened and each cyl inder will operate under three quarter load.

On the next step the auxiliary valve 3 opens and admits pressure to the valve lifter cyllnders-and the inlet valves and 7- at the head ends of the compressor cylinders, which still further unloads the compressor causing it to operate at one-half load. The clear ance valves may continue to remain open, although, if desired, the apparatus could be so constructed that these valves would automatically close at this point. The third step of operation is effected by the auxiliary valve 9 which causes the inlet valves 0 and s at the crank ends of the cylinders to be held open while maintaining the inlet valves 70 and nopen, thus fully unloadingthe compressor. As the auxiliary valves operate in reverse order the compressor is first placed under one-half load, then three-quarter load, then full load.

It is to be understood that any desired number of steps of unloading and loading may be eii'ected, but in this instance the step of one-quarter loading is omitted, for simplicity and for particular application to certain kinds of duty for the compressor.

I claim:

1. In a compressor unloader, the combination of a cylinder having heads and apiston, inlet and discharge valves, a single clearan ce chamber in the air head at the head end of the cylinder, a clearance valve for said chamber, and means for unloading the compressor in three successive steps only by first opening the clearance valve, then holding an inlet valve open at the head end of the cylinder, and lastly holding an inlet valve open at the crank end of the cylinder for complete unloading.

2. Ina compressor unloader, the combination of a cylinder having heads and a piston,

inlet and'discharge valves,a single clearance chamber in the air head at the head end of the cylinder, a clearance valve for said chamber, and automatic unloading devices responsive to the rise in discharge pressure for unloadingthe compressor step by step, in three successive steps only, by first opening the clearance valve, then holding an inlet valve open at the head end of the cylinder, andlastly holding an i-nlet valve open at the crank end of the cylinder for complete unloading.

3. In a, compressor unloader, the combination of a cylinder having heads and a piston, inlet and discharge valves, a single clearance chamber in the air head at the head end of the cylinder, a clearance valve for said chamher, and automatic unloading devices responsive to the rise in discharge pressure for unloading the compressor step'by step, in three successive steps only, by first opening the clearance valve, then holding an inlet valve open at the head end of the cylinder, and lastl holding an inlet valve open at the cran end of the cylinder for complete unloading, said automatic unloading devices also operating to load the compressor step by step in reverse order as the discharge pressure falls. A 1 I In testimony whereof I have signed this specification.

HARRY v. HAIGHT. 

